Tracheostomy tubes are used to assist a patient to breathe. The tube is inserted in a patient's throat through a puncture wound below an obstruction. When in place, the tube provides a direct connection between an oxygen or air source and the trachea.
A common type of tracheostomy tube is equipped with inner and outer cannulae; the inner cannula fitting within the outer cannula. The inner cannula is provided with a connector body while the outer cannula is provided with a connector head. The connector body and connector head interlock to secure the inner cannula within the outer cannula. A breathing apparatus connector slides over this connection to provide a complete air circuit.
The inner cannula is removable if obstructed. When the inner cannula is removed, the outer cannula maintains the oxygen or air path to the trachea. To assist in its removal, and to avoid discomfort to the patient, the disposable cannula should be easily detached from the outer cannula. Ease in detachment is particularly important where the patient is connected to a ventilator because it is likely that the patient is unable to breathe on his own while the changeover is accomplished.
Many tubes in the prior art employ manually clamping of the inner cannula to the outer cannula. Crandall, U.S. Pat. No. 4,009,720 employs a device with two clamps having short, cantilevered actuator arms attached to hooks. The clamps are connected to the disposable cannula and the actuator arms are substantially in the same plane as the connection point for the clamps. The clamp is operated by pressing the cantilevered actuator arms, thereby causing the hooks to rotate to an open position against the torque from a flexible hinge. Once the disposable cannula is properly inserted into the outer cannula, pressure is released and the hooks secure the cannulae together. To prevent breakage from an over-extension of the hinge, stops are provided for the clamps. Similar devices are disclosed in Crandall, et al., U.S. Pat. No. 3,639,624, Crandall et al., U.S. Pat. No. 4,135,505, Eisele, U.S. Pat. No. 5,067,496, and Abel, U.S. Pat. No. 5,067,515.
Other tubes employ friction-fit locking devices. U.S. Pat. No. 4,052,990 to Dodgson discloses a typical tubing adaptor that is assembled with an endotracheal tube such as a tracheostomy tube. The device comprises a molding having a cup shaped body portion with an internal stem. The stem has an outwardly flared lip. This lip is engaged by the tube to provide a friction fit without a positive locking connection. Consequently, this connector is subject to accidental disconnections.
While these clamps adequately secure the inner cannula to the outer cannula, accidental disconnections have occurred because the patient is capable of unfastening the inner cannula while the tracheostomy tube is connected to a ventilator or other breathing apparatus. It is desirable for devices connecting tracheal tubes and breathing apparatus or other oxygen or air sources be able to avoid accidental disconnection, even when subjected to aggressive manipulation by an active patient. There is a need for a locking system that prevents detachment of the cannulae, while at the same time, allows easy detachment of the inner cannula by the care giver.